Project Summary Gay and bisexual men and other sexual minority men (SMM) in the U.S. are burdened by a high and disproportionate rate of HIV infection. Improving outcomes of the HIV Care Continuum through to maintaining viral load (VL) suppression is associated with a significant reduction in the sexual transmission of HIV and significantly better long-term health outcomes. However, little research provides insight into the preventable structural, psychosocial, and behavioral factors that influence durable VL suppression during early infection that can be used in developing effective early intervention strategies. Moreover, the successful implementation of TasP and U=U messaging is a necessary component of the strategy to end the HIV epidemic, but rigorous research is needed to address real-world implementation issues, including safety concerns and perceived barriers among key stakeholder populations. We aim to address these issues with two studies grounded in the Social Ecological Model (SEM) to simultaneously examine both VL suppression and implementation barriers surrounding U=U from multiple levels of influence. Specifically, Aim 1 of the study is to examine time to initial VL suppression and patterns in VL rebound to better understand the dynamic nature of VL suppression and use the SEM along with an intersectional minority stress framework to longitudinally investigate structural, psychosocial, and behavioral factors associated with VL suppression among SMM to better understand risk and resilience. Next, Aim 2 is to examine how adherence and perceived VL status are associated with objective VL status and whether concordance between perceived and actual VL suppression influences sexual risk compensation as captured by event-level sexual behaviors and STI infections. Finally, Aim 3 is designed to understand ongoing barriers to implementing U=U from the perspectives of the three populations critical to its successful implementation among SMM?namely, SMM living with HIV, HIV-negative SMM, and HIV care providers. To do so, Study 1 (Aims 1 and 2) will leverage two LITE cohorts to recruit 250 SMM newly diagnosed with HIV during the course of the studies?we will follow these men for two years immediately following diagnosis, collecting home-based dried blood spot for VL on a monthly basis to examine the dynamic nature of VL suppression. In addition to VL and self-reported data, the study will include objective indicators of adherence and care engagement as well as qualitative interviews. The goal of Study 1 will be to identify risk and resilience factors that influence VL suppression and can be used to guide future intervention development (Aim 1) while simultaneously addressing understudied safety concerns of implementing U=U with regard to unintended risks (Aim 2). In Study 2 (Aim 3), we will use focus groups conducted three times over five years to inform implementation of U=U messaging. Achieving the aims of the proposed study will provide key insights that will be critical for translating to or adapting interventions to enhance their potency and durability and improve the health of SMM living with HIV and curb new infections.